vehicle sinks

hello ,
when i add my vehicle to udk half of the car tires sinks to the ground i don’t understand where is the problem

Is it actually a vehicle that extends the vehicle class, or is it just a mesh that looks like a vehicle? Where is the origin for your model? Have you tried just raising the model some more before exporting it? If it’s actually a vehicle, how does it work otherwise? If you place it in the editor, does it look fine in the editor, but then it sinks when you start the game? I think we need some more information from you before we can even begin guessing at what’s wrong.

it’s a carriage extends from the scorpion it moves normally but the wheels half o it is hidden under the terrain i think that tweeking the wheel radius help